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Fencer Intel
medium 4.3

CVE-2026-100621 json

capgo.app Content-Lock Bypass via r2-direct Bundle Mutation

published last mo. modified last mo. also EUVD-2026-87716

cvss
4.3
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.3%
EPSS 0.3% chance of exploitation in 30 days, percentile 18%
public exploits
0
none known

Summary

Capgo (capgo.app) contains an incomplete access-control/content-lock enforcement issue affecting all versions; no patch is available at the time of publication. The `enforce_encrypted_bundle_trigger` / `check_encrypted_bundle_on_insert` content lock in supabase/schemas/prod.sql exempts `app_versions` rows whose previous `storage_provider` is `r2-direct`, so delivery-critical columns (name, app_id, session_key, key_id, storage_provider, r2_path, external_url, checksum, manifest, native_packages) remain mutable while a row is in that state. Separately, the channel/version join used by the `/updates` endpoint (supabase/functions/_backend/utils/pg.ts) filters only deleted versions and does not exclude `r2-direct` versions, so such rows remain OTA-selectable. An attacker holding a Capgo API key with bundle write/upload permission can create or keep a bundle version in the `r2-direct` state, assign it to a channel, and then modify these fields via direct PostgREST requests, causing altered bundle metadata (for example checksum and session_key) to be served to devices through `/updates`. This bypasses the post-upload content immutability hardening added for a previous app_versions metadata-tampering issue.

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CISA SSVC

Exploitation
Proof of concept is public
Automatable
no
Technical impact
partial
Assessed
last mo.

Exploit prediction

0.27% chance of exploitation in the next 30 days, higher than 18% of all scored CVEs (FIRST EPSS, 2026-11-09).

Exploits and checks

  • github.com https://github.com/Cap-go/capgo.app/security/advisories/GHSA-5rg9-rhwj-wj76 referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
CNA 4.0 5.3 CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N
CNA 3.1 4.3 CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:N
CNA 4.0 5.3 CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

Affected products

  • Cap-go capgo.app

Classification

Weakness

References

Sources

Fencer Intel keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.